F1: Alonso fastest in first practice in Australia

MELBOURNE - Ferrari's Fernando Alonso topped the timesheets in the first free practice at the Australian Grand Prix on Friday as reliability problems saw the new Formula One season open with a whimper rather than a bang.

The two-time world champion Spaniard posted a lap of one minute 31.840 seconds with half an hour left in the 90 minute session and held his half-a-second lead over McLaren's second-placed Jenson Button in brilliant sunshine at Albert Park.

After a winter testing in which teams struggled to come to terms with the new turbocharged hybrid engines, drivers spent much of the session cooling their heels in the garages, while technicians tinkered.

The biggest surprise of the session was trouble for Mercedes, who arrived Down Under optimistic after a promising winter testing.

Having batted away the favorites to win the season-opener tag, Lewis Hamilton was left fuming when his car stopped at turn nine of his installation lap just five minutes into the session.

With the vehicle hauled off by a tow-truck, the 29-year-old Briton walked back to the paddock without taking his helmet off and suffered the indignity of being stopped by security before retreating into his team's tent.

Mercedes later issued a statement clarifying that his car had come to an automatic halt triggered by an oil pressure alarm, but said they needed to investigate the fault further.

Mercedes-powered Williams fared better, with Valtteri Bottas posting the third-fasted time and his new teammate Felipe Massa shrugging off a radio malfunction to be fourth quickest.

Red Bull, who endured a dismal winter testing, had an encouraging first session, with new driver Daniel Ricciardo finishing fifth ahead of reigning quadruple world champion Sebastian Vettel in seventh.

Hamilton's teammate Nico Rosberg was sixth for Mercedes, while Kimi Raikkonen, taking his first run for Ferrari since returning to Maranello, was ninth after eighth-placed McLaren debutant Kevin Magnussen.

Lotus waited until 20 minutes left in the session before making an appearance, with driver Pastor Maldonado rolling out of the garage, but he managed only an installation lap before taking a skid through some gravel and coming to a halt in pit-lane.

He and teammate Romain Grosjean were among five drivers that failed to post a lap time, suggesting plenty of work to be done before the second practice session later on Friday. - Reuters